/*
 * Tencent is pleased to support the open source community by making spring-cloud-tencent available.
 *
 * Copyright (C) 2021 Tencent. All rights reserved.
 *
 * Licensed under the BSD 3-Clause License (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://opensource.org/licenses/BSD-3-Clause
 *
 * Unless required by applicable law or agreed to in writing, software distributed
 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */

package com.tencent.cloud.polaris.eager.instrument.feign;

import java.lang.reflect.Field;
import java.lang.reflect.Proxy;
import java.net.URI;

import com.tencent.cloud.polaris.discovery.PolarisDiscoveryClient;
import com.tencent.cloud.polaris.discovery.reactive.PolarisReactiveDiscoveryClient;
import com.tencent.polaris.api.utils.StringUtils;
import feign.Target;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.context.ApplicationContext;
import org.springframework.context.SmartLifecycle;

public class FeignEagerLoadSmartLifecycle implements SmartLifecycle {

	private static final Logger LOG = LoggerFactory.getLogger(FeignEagerLoadSmartLifecycle.class);

	private final ApplicationContext applicationContext;

	private final PolarisDiscoveryClient polarisDiscoveryClient;

	private final PolarisReactiveDiscoveryClient polarisReactiveDiscoveryClient;

	public FeignEagerLoadSmartLifecycle(ApplicationContext applicationContext, PolarisDiscoveryClient polarisDiscoveryClient,
			PolarisReactiveDiscoveryClient polarisReactiveDiscoveryClient) {
		this.applicationContext = applicationContext;
		this.polarisDiscoveryClient = polarisDiscoveryClient;
		this.polarisReactiveDiscoveryClient = polarisReactiveDiscoveryClient;
	}

	@Override
	public void start() {
		LOG.info("feign eager-load start");
		for (Object bean : applicationContext.getBeansWithAnnotation(FeignClient.class).values()) {
			try {
				if (Proxy.isProxyClass(bean.getClass())) {
					Target.HardCodedTarget<?> hardCodedTarget = getHardCodedTarget(bean);
					if (hardCodedTarget != null) {
						FeignClient feignClient = hardCodedTarget.type().getAnnotation(FeignClient.class);
						// if feignClient contains url, it doesn't need to eager load.
						if (StringUtils.isEmpty(feignClient.url())) {
							// support variables and default values.
							String url = hardCodedTarget.name();
							// refer to FeignClientFactoryBean, convert to URL, then take the host as the service name.
							if (!url.startsWith("http://") && !url.startsWith("https://")) {
								url = "http://" + url;
							}
							String serviceName = URI.create(url).getHost();

							LOG.info("[{}] eager-load start", serviceName);
							if (polarisDiscoveryClient != null) {
								polarisDiscoveryClient.getInstances(serviceName);
							}
							else if (polarisReactiveDiscoveryClient != null) {
								polarisReactiveDiscoveryClient.getInstances(serviceName).subscribe();
							}
							else {
								LOG.warn("[{}] no discovery client found.", serviceName);
							}
							LOG.info("[{}] eager-load end", serviceName);
						}
					}
				}
			}
			catch (Exception e) {
				LOG.debug("[{}] eager-load failed.", bean, e);
			}
		}
		LOG.info("feign eager-load end");

	}

	public static Target.HardCodedTarget<?> getHardCodedTarget(Object proxy) {
		try {
			Object invocationHandler = Proxy.getInvocationHandler(proxy);

			for (Field field : invocationHandler.getClass().getDeclaredFields()) {
				field.setAccessible(true);
				Object fieldValue = field.get(invocationHandler);
				if (fieldValue instanceof Target.HardCodedTarget) {
					return (Target.HardCodedTarget<?>) fieldValue;
				}
			}
		}
		catch (Exception e) {
			if (LOG.isDebugEnabled()) {
				LOG.debug("proxy:{}, getTarget failed.", proxy, e);
			}
		}
		return null;
	}

	@Override
	public void stop() {

	}

	@Override
	public boolean isRunning() {
		return false;
	}

	@Override
	public int getPhase() {
		return 10;
	}
}
